Pressure Switch Cartridge Principle of Operation

As the pressure increases, the diaphragm flexes and pushes the shaft upwards.
Depending on the offset distance of the shaft, it pushes the electrical contact upwards and disconnects the contacts 5 and 6.
When the pressure decreases, the diaphragm recedes, bringing the shaft and the electrical contact down, where the contacts 5 and 6 are connected.